This invention relates generally to the art of seals, and is concerned in particular with neck seals of the type employed on roll necks in rolling mills.
In a typical rolling mill installation, a roll neck is journalled for rotation in an oil film bearing. The bearing includes a sleeve keyed or otherwise fixed to the roll neck for rotation therewith. The sleeve is surrounded by and supported within a non-rotatable bushing which is in turn contained in a bearing chock. An oil film is maintained between the sleeve and the bushing during operation of the mill. A seal assembly is employed both to prevent loss of oil from the bearing, and also to prevent exterior contaminants such as cooling water, mill scale, etc. from penetrating into the bearing.
Typical of the prior art seal assemblies which have heretofore been developed are those described in U.S. Pat. Nos. 2,868,574; 3,093,425; 3,330,567; 3,545,774 and 3,832,021, all having been assigned to the same assignee as that of the present invention. These prior art seal assemblies each typically include a one-piece neck seal having a flexible circular body mounted on a tapered transition section of the roll neck, with resilient flanges which extend radially outwardly from the seal body. The peripheral edges of the resilient flanges are adapted to frictionally contact surrounding shoulders on a non-rotatable seal end plate. Oil is retained in the bearing by the seal provided at the interface between one of the rotating resilient seal flanges and the non-rotatable seal end plate shoulder in contact therewith. Likewise, contaminants are excluded from the bearing by the seal provided at the interface between the other of the rotating resilient seal flanges and its associated seal end plate shoulder.
Although the neck seals of these conventional seal assemblies have operated for many years in a generally satisfactory manner, there have been several problems associated with their use. For example, because the neck seals are molded as a single integral unit, when leakage occurs due to wear of the peripheral flange edges, the entire seal must be replaced. The replacement of entire seals when only their flanges are worn represents an unnecessary expense to mill owners.
Also, because conventional seals are molded as a single unit, the same flexible material must be used for all portions of the seal. However, the ideal material for the resilient flanges may not be suitable for the body portion which must sealingly engage the roll neck. Thus a compromise usually must be made when selecting a single material which is acceptable for all sections of the seal. Such compromises prevent the seal manufacturer from using the best available material for the seal flanges, and thus limit the useful life of the seal to something less than it might otherwise be if the manufacturer had more latitude in the selection of available materials.
Another problem with conventional one-piece seals relates to the difficulty of accurately locating reinforcing elements such as metal bands in the seal body.
Accordingly, a general object of the present invention is to provide a novel and improved seal which obviates or at least substantially minimizes the problems mentioned above.
A more specific object of the present invention is the provision of a seal comprised of separately manufactured inner and outer flexible body segments.
A further object of the present invention is the provision of a seal having inner and outer flexible body segments which are separately manufactured of different materials, with the material for the outer body segment being ideally suited for providing long-wearing resilient flanges, and with the material for the inner body segment being ideally suited for mounted on the roll neck in sealing engagement therewith.
A still further object of the present invention is the provision of a seal comprised of separately manufactured inner and outer flexible body segments interconnected in a manner which permits replacement of a worn outer body segment without also having to replace the inner body segment.
Another object of the present invention is to provide a seal comprised of inner and outer flexible body segments, with a reinforcing element such as for example a metallic band integral with the outer body segment.